Field of the Invention
Embodiments of the invention relate to an organic light emitting diode display having an electricity generation function.
Discussion of the Related Art
Since an organic light emitting diode (OLED) display is a self-emission display device, the OLED display may be manufactured to have lower power consumption and a thinner profile than a liquid crystal display requiring a backlight unit. Further, the OLED display has advantages of a wide viewing angle and a fast response time. The process technology of the OLED display has also been developed for large-screen mass productions. As a result, the OLED display has expanded its market while competing with the liquid crystal display.
According to a related art, each pixel of the OLED display includes an organic light emitting diode (OLED) having a self-emitting structure. As shown in FIG. 1, organic compound layers including a hole injection layer HIL, a hole transport layer HTL, an emission layer EML, an electron transport layer ETL, an electron injection layer EIL, etc. are stacked between an anode and a cathode of the OLED. The OLED display implements an input image using a phenomenon in which the OLED emits light when electrons and holes are combined in an organic layer through a current flowing in a fluorescence or phosphorescence organic thin film.
The OLED display may be variously classified depending on the kinds of emission materials, an emission method, an emission structure, a driving method, and the like. The OLED display may be classified into a fluorescent emission type and a phosphorescent emission type depending on the emission method. Further, the OLED display may be classified into a top emission type and a bottom emission type depending on the emission structure. Further, the OLED display may be classified into a passive matrix OLED (PMOLED) display and an active matrix OLED (AMOLED) display depending on the driving method.
Each pixel of the OLED display includes a driving thin film transistor (TFT) for controlling a driving current flowing in the OLED depending on data of the input image. Characteristics such as a threshold voltage and a mobility of the driving TFT have to be uniformly designed in each and all of the pixels of the OLED display, but generally are not uniform depending on a process deviation, a driving time, a driving environment, etc. Thus, the OLED display has adopted a compensation technology for sensing changes in the driving characteristics of the pixels to properly modify input data based on the sensed result. The changes in the driving characteristics of the pixel include changes in the characteristics of the driving TFT including the threshold voltage, the mobility, etc. of the driving TFT.
The structure of the OLED is similar to the structure of a battery cell of an organic solar cell. A study has been proposed to combine the OLED and the organic solar cell and generate electric power of the organic solar cell using light of the OLED. However, such a study has to involve studying the changes in the structure of the OLED. Therefore, the proposal results in an increase in the manufacturing cost of the display device and makes it difficult to achieve lightness in weight and the thin profile of the display device.